Building on fairness heuristic theory and dual-process theories of cognition, we examine individuals' perceptions of phase-shifting. We define phase-shifting as an individual perception that triggers a shift from type 1 to type 2 cognitive processes resulting in the reevaluation of justice judgments. In a longitudinal study of a merger, we empirically test the influence of phase-shifting perceptions on justice judgments, and we identify antecedents of phase-shifting perceptions. We find employees' perceptions of the change as a phase-shifting event moderates the relationship between overall justice judgments prior to change (time 1), and subsequent assessments of justice 6 months later (time 2). We study three situational antecedents (i.e., magnitude of change, managerial exemplarity, and coworker support for change) and one individual antecedent (i.e., dispositional resistance to change) of phase-shifting perceptions. The four hypothesized antecedents together predict 75% of employees' perceptions of the merger as a phase-shifting event. Implications for research and practice regarding organizational justice and organizational change are discussed.